@type t() :: %Angelus.Astro.Point{
  declination: float() | nil,
  declination_rad: float() | nil,
  et_seconds: float() | nil,
  longitude_rad: float() | nil,
  metadata: map() | nil,
  point: atom(),
  speed_rad_day: float() | nil
}

Mathematical point state.

Fields:

• :point - the point atom (e.g. :true_node, :lilith).
• :longitude_rad - ecliptic longitude in radians.
• :declination and :declination_rad - true-equatorial declination of date.
• :speed_rad_day - longitude speed in radians per day.
• :et_seconds - ephemeris time / TDB seconds past J2000.
• :metadata - internal metadata map (engine, kernels, source point, etc.).